[ISSUE #12130] add metadata as labels in prometheus http sd

prometheus/src/main/java/com/alibaba/nacos/prometheus/utils/PrometheusUtils.java

@@ -36,21 +36,36 @@ public class PrometheusUtils {
 
     /**
      * Assemble arrayNodes for prometheus sd api.
-     *
      */
     public static void assembleArrayNodes(Set<Instance> targetSet, ArrayNode arrayNode) {
         Map<String, List<Instance>> groupingInsMap = targetSet.stream().collect(groupingBy(Instance::getClusterName));
         groupingInsMap.forEach((key, value) -> {
-            ObjectNode jsonNode = JacksonUtils.createEmptyJsonNode();
-            ArrayNode targetsNode = JacksonUtils.createEmptyArrayNode();
-            ObjectNode labelNode = JacksonUtils.createEmptyJsonNode();
-            value.forEach(e -> {
-                targetsNode.add(e.getIp() + ":" + e.getPort());
-            });
-            labelNode.put("__meta_clusterName", key);
-            jsonNode.replace("targets", targetsNode);
-            jsonNode.replace("labels", labelNode);
-            arrayNode.add(jsonNode);
+            for (Instance instance : value) {
+                ObjectNode jsonNode = assembleInstanceToArrayNode(key, instance);
+                arrayNode.add(jsonNode);
+            }
         });
     }
+
+    /**
+     * assemble instance to json node, and export metadata to label.
+     *
+     * @param clusterName the cluster name
+     * @param instance    instance info
+     */
+    private static ObjectNode assembleInstanceToArrayNode(String clusterName, Instance instance) {
+
+        ArrayNode targetsNode = JacksonUtils.createEmptyArrayNode();
+        targetsNode.add(instance.getIp() + ":" + instance.getPort());
+        ObjectNode labelNode = JacksonUtils.createEmptyJsonNode();
+        //mark cluster name
+        labelNode.put("__meta_clusterName", clusterName);
+        //export metadata
+        Map<String, String> metadata = instance.getMetadata();
+        metadata.forEach(labelNode::put);
+        ObjectNode jsonNode = JacksonUtils.createEmptyJsonNode();
+        jsonNode.replace("targets", targetsNode);
+        jsonNode.replace("labels", labelNode);
+        return jsonNode;
+    }
 }

prometheus/src/test/java/com/alibaba/nacos/prometheus/controller/PrometheusControllerTest.java

@@ -39,7 +39,9 @@
 import org.springframework.test.web.servlet.setup.MockMvcBuilders;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 
 import static org.junit.Assert.assertEquals;
 import static org.mockito.Mockito.when;
@@ -77,12 +79,18 @@ public void setUp() throws NoSuchFieldException, IllegalAccessException, NacosEx
         service = Service.newService(nameSpace, group, name);
         serviceManager.getSingleton(service);
         testInstanceList = new ArrayList<>();
+        testInstanceList.add(prepareInstance("A", "127.0.0.1", 8080, Collections.singletonMap("__meta_key", "value")));
+        testInstanceList.add(prepareInstance("A", "127.0.0.1", 8081, Collections.singletonMap("__meta_key", "value2")));
+        mockMvc = MockMvcBuilders.standaloneSetup(prometheusController).build();
+    }
+
+    private Instance prepareInstance(String clusterName, String ip, int port, Map<String, String> metadata) {
         Instance instance = new Instance();
         instance.setClusterName("A");
         instance.setIp("127.0.0.1");
         instance.setPort(8080);
-        testInstanceList.add(instance);
-        mockMvc = MockMvcBuilders.standaloneSetup(prometheusController).build();
+        instance.setMetadata(metadata);
+        return instance;
     }
 
     @After